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In Linux it is possible to change a user's password with the ouput of an echo command, coming from standard input, via pipe.
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NAME
passwd - update a user’s authentication tokens(s)

SYNOPSIS
passwd [-k] [-l] [-u [-f]] [-d] [-n mindays] [-x maxdays] [-w warndays] [-i inactivedays] [-S] [--stdin] [user-
name]

DESCRIPTION
Passwd is used to update a user’s authentication token(s).

Passwd is configured to work through the Linux-PAM API. Essentially, it initializes itself as a "passwd" service
with Linux-PAM and utilizes configured password modules to authenticate and then update a user’s password.

A simple entry in the Linux-PAM configuration file for this service would be:

#
# passwd service entry that does strength checking of
# a proposed password before updating it.
#
passwd password requisite \
/usr/lib/security/pam_cracklib.so retry=3
passwd password required \
/usr/lib/security/pam_unix.so use_authtok
#

Note, other module-types are not required for this application to function correctly.

OPTIONS
-k The option, -k, is used to indicate that the update should only be for expired authentication tokens
(passwords); the user wishes to keep their non-expired tokens as before.

-l This option is used to lock the specified account and it is available to root only. The locking is per-
formed by rendering the encrypted password into an invalid string (by prefixing the encrypted string with
an !).

--stdin
This option is used to indicate that passwd should read the new password from standard input, which can be
a pipe.
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[b]Example of reading password from standard input:[/b]
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# echo '123456789' | passwd --stdin tuser
Changing password for user tuser.
passwd: all authentication tokens updated successfully.
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Above, user tuser's password was changed to '123456789'.